1. Field of the Invention
This invention relates to a photographic camera and in particular to a camera system including an accessory-mountable camera body and one or more accessories such as an interchangeable lens, automatic wind-up device, flashing device, etc. More specifically, the present invention relates to a camera system including a camera body and at least one accessory in which a current signal is used to establish cooperation between the camera body and the accessory.
2. Description of the Prior Art
In a prior art camera system including a camera body and an accessory mounted on the camera body, a signal to be transmitted between the camera body and the accessory is generally a simple ON/OFF signal. In transmitting an analog signal from either one of the camera body and the accessory to the other, it has been required to adjust the supply voltages of the camera body and the accessory equal in level so that the system may be operated virtually by a common supply voltage. Thus, if information is to be transmitted by a simple ON/OFF signal, the contents of information are necessarily limited to rudimentary control and warning. On the other hand, if supply voltages same in level are to be used, versatility of the camera system is limited. For example, only exclusive accessories are allowed to be used for a particular type camera body.